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or Foreign. Relatians dealing with salinity in areas where there is 25 ar 30 inches af rainfall. Of caurse, if the moisture of heaven, fresh and pure, is mixed with an equal amount of irrigatian water, the salinity is cut in half. In the territary referred to, the rainfall is 20 or 25 inches; but dawn in our deserts far years at a time there is not enough rainfall to get down to. the graund. "Mr. President, this is the simple fact: The experts are all agreed that the present salinity af Lake Mead is abaut 7 SO parts per millian. In 25 ar .30 years, due to. greater use in the upper basin States, it will probably approach 1,000 parts per million. That is fairly goad water for irrigation. That is what we in the lawer basin hape to get for our first application of that water. "The distinguished Senatar from Calorada reiterated that the use af the water once, in the lower basin States, wauld nat depreciate its quality very much. Let us see what the facts are, as developed by the experts. To. obtain advice on this question, I went to the Department of Agriculture. The department recom- mended to me the man conSidered the most expert on salinity in the United States, Suppose that, in Arizona, 4 acre-feet af water, impregnated with salinity to. a degree of 1,000 parts per million, were applied to an acre of ground. It must be under- stoad that 3 af thase acre-fee:t wauld be taken up by the plants and by evaparatian, and there wauld be approximately 1 acre-faot af return flow. I origll1ally calculated that if the <)raund were not becoming mare saline, the 1 acre-foot of return flow wauld have to. carry as much salt uS had been carried by th8 original 4 acre- feet, 0.1' four tim8S as much. So I thought that the water which wauld come aft the Arizana iands would be impregnated with 4,000 parts of salt per million; and since water becomes non- usable when it has 2,000 or 3, 000 par~~j)er millian,_.Qlc.o_ur,se _ ___ I was disturbed. However, the experts showed me that I was wrong, because aut of this salty water certain of the salts are precipitated anta the soil. They are generally the harmless salts. They are nat carried aut by the return flaw. "Sa the actual records show that the kind of water being used by Arizona wauld have its salinity increased, by one application far irrigation, from a thausand purts to. 2,700 parts per million. That is because 1 acre-foot of water wauld then have to. hald the salt farmerly held in solutian by 4 acre-feet, less the amount of salt precipitated in the land. Water with 2,700 parts per millian, af caurse, is unusable water, and Mexico. will never take it." On page 3175 Senator Downey again expressed hlS concern over the quality questian. It was his pasition that in spite of the claim of the State B 41